Salted Caramel Brownies

Salted Caramel Brownies
1 C unsalted butter
4 T cocoa powder
1 tsp. espresso powder (optional)
1 oz. unsweetened chocolate baking bar
2 C all-purpose (AP) flour
2 C granulated sugar
pinch of salt
4 eggs
1 T vanilla extract
1/2 C semi-sweet chocolate chips
1/2 C English toffee bits
1/2 C caramel topping
coarse Sea Salt crystals
1/4 C walnuts, chopped (if desired)
Heat oven to 350°F. In a small saucepan over medium low heat, combine the butter, cocoa, espresso* (if desired), and the unsweetened chocolate bar until melted and smooth. Remove from heat and set aside to cool. In a medium bowl, combine flour, sugar and salt. Pour the chocolate mixture over the flour mixture and with a mixer, beat on low to combine. Add the eggs, one at a time, beating after each addition. Add the vanilla and beat for one minute. Add the chocolate chips and toffee bits and stir just to combine. Pour the mixture into a 9 x 13 baking dish or a divided brownie pan** greased or sprayed with cooking spray. Bake the 9x13 for 30 minutes, and the divided pan for 18 minutes.  When done, remove from oven and immediately drizzle with the caramel sauce, it helps to warm the caramel sauce in the microwave to soften for about 20 seconds. Once the caramel is on, sprinkle lightly with the sea salt. If you'd like you can sprinkle the top with the chopped walnuts too.
*Using the espresso powder is optional, however, I find that it enhances the chocolate flavor.
**Makes 21 brownies using a large scoop to put into each section of the pan.